This invention relates generally to industrial baghouses and deals more particularly with an improved filter bag assembly which may be installed or removed either upwardly or downwardly from the tube sheet of a baghouse.
Continuous emphasis on environmental quality has resulted in increasingly strenuous regulatory controls on industrial emissions. One technique which has proven highly efficient in controlling air pollution has been separation of undesirable particulate matter from a gas stream by fabric filtration.
Such filtration is carried out in dust collection apparatus known in the trade as a "baghouse" which operates on the same general principle as an ordinary household vacuum cleaner, except on a much larger scale. Basically, the baghouse is a sheet metal housing divided into two chambers, referred to as plenums, by one or more tube sheets. Disposed within openings communicating with the plenums are fabric filters. A particle laden gas stream, induced by the action of a fan, flows into one chamber (dirty air plenum) wherein dust accumulates on the fabric filter as the gas passes through the fabric into the other chamber (clean air plenum) and out the exhaust.
Although all baghouses are designed in accordance with the foregoing general principles, there are numerous operational and structural distinctions. The present invention relates to a baghouse in which the dirty and clean air plenums are separated by a tube sheet having a plurality of vertically suspended filter bags that receive cylindrical wire cages for skeletal support. Filtration of the process gas occurs from outside to inside of the bag. Therefore, baghouses constructed in this manner are normally referred to as outside bag collectors. An example of this type of baghouse is disclosed in my U.S. Pat. No. 4,097,254, which is incorporated herein by reference.
It is inevitable that, in service, the filter bags will develop leaks or other damage which impairs their effectiveness in removing particulate matter from contaminated gas. In order to stay within industrial emissions standards and operate at peak efficiency, it is imperative that defective bags be identified and replaced. Therefore, maintaining the bags in proper condition is of crucial importance to operation of the baghouse.
The replacement of defective bags has traditionally been a time consuming and costly maintenance operation which often requires a number of workers. With the top access doors opened, the bags and associated rigid cages can normally be removed from the tube sheet in an upwardly direction. Where there is little room above the baghouse, as may be encountered in a low ceiling building, this manner of removal of the bags which are typically 8 feet or more in length is difficult or in some cases impossible. Even if there is sufficient room for upward removal of the bags, the workmen must often work in cramped quarters which greatly increases the difficulty of the task and the time required to complete it.
Therefore, it is apparent that a need exists for a filter bag assembly which can be easily removed from its supporting tube sheet in a downwardly direction as well as upwardly when bag replacement is necessary, and which can easily be installed from beneath the tube sheet. The primary goal of the present invention is to meet this need.
More specifically, it is an object of the invention to provide a filter bag and cage assembly which can be quickly and easily installed or removed from beneath the tube sheet of the baghouse. The hanger arrangement which supports the case within the filter bag permits convenient bottom installation or removal in situations where there is insufficient clearance space above the baghouse to enable installation from above or upward removal of the rigid cages. If there is sufficient clearance above the baghouse, installation or removal from above may be carried out with equal convenience.
Another object of the invention is to provide a filter bag and cage assembly of the character described in which the cage is supported on the sturdy upper rim structure of the filter bag rather than on the bottom of the bag.
A further object of the invention is to provide the fiter bag and cage assembly of the character described wherein standard filter bags may be employed and there is no need for significant modification of the tube sheet.
An additional object of the invention is to provide a filter bag and cage assembly of the character described which is constructed simply and economically.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description of the drawings.